US4128571A - Thermal conversion of 4-cyano-suberonitrile to acrylonitrile - Google Patents
Thermal conversion of 4-cyano-suberonitrile to acrylonitrile Download PDFInfo
- Publication number
- US4128571A US4128571A US05/846,100 US84610077A US4128571A US 4128571 A US4128571 A US 4128571A US 84610077 A US84610077 A US 84610077A US 4128571 A US4128571 A US 4128571A
- Authority
- US
- United States
- Prior art keywords
- suberonitrile
- cyano
- acrylonitrile
- sec
- reactor
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C253/00—Preparation of carboxylic acid nitriles
- C07C253/30—Preparation of carboxylic acid nitriles by reactions not involving the formation of cyano groups
Definitions
- the invention relates to the production of acrylonitrile from 4-cyano-suberonitrile.
- a long standing problem in the manufacture of adiponitrile from acrylonitrile by electrolytic dimerization has been the loss of adiponitrile by way of conversion to the by-products propionitrile and 4-cyano-suberonitrile, which, in a typical electrohydrodimerization reaction, occurs at a rate of about 8-14 mole % of the acrylonitrile employed at a starting material. Of this amount 4-7 mole % is attributable to losses involving conversion of acrylonitrile to the 4-cyano-suberonitrile.
- a reaction for converting the 4-cyano-suberonitrile to acrylonitrile at a commercially acceptable conversion and selectivity rate would be a significant advance in the art and is an object of this invention.
- 4-cyano-suberonitrile is continuously converted to acrylonitrile by passing the 4-cyano-suberonitrile in atomized form through an substantially oxygen and catalyst-free reaction zone at about 700°-800° C. at an hourly space velocity of about 2400-9300 and a linear velocity of 5-20 ft/sec (152.4-609.6 cm/sec). Within the above ranges, linear velocity and space velocity are adjusted in order to obtain, in relation to the selected temperature, the best conversion rate of 4-cyano-suberonitrile, without sacrifice of an acceptable selectivity rate of the acrylonitrile.
- 4-cyano-suberonitrile may be employed as feedstock in the relatively impure form in which it is produced by electrohydrodimerization and recovered from the reactor by conventional distillation procedures. Providing it does not contain material deleterious to the reaction or the products, percent of purity is not critical. It is preferably diluted with an inert gas such as nitrogen, or a relatively inert noninterferring diluent such as steam. In order to prevent clogging of nozzles feeding the reactor it may be desirable to use propionitrile as a diluent.
- the feedstock, pure or diluted, is preferably atomized prior to or during the course of being fed into the reactor but it may be fed in liquid form into the reactor thereafter to be atomized.
- Space velocity is defined as the volume of gas per hour divided by the reactor volume.
- linear velocity is defined as the number of cubic units of gas per second divided by the cross sectional area of the reaction zone in square units.
- the length to diameter ratios of the reactor must be chosen so that the linear and space velocities will come within the requirements of the invention.
- the volume of 4-cyano-suberonitrile is calculated at the temperature and pressure prevailing in the reactor at operating conditions.
- 4-cyano-suberonitrile (70.5 wt %) was introduced into a 10 foot (304.8 cm) by 1/4 inch (7.62 cm) stainless steel (304) reactor having a 2 foot ⁇ 1/4 inch stainless steel preheater section at temperatures of 650°-750° C. and at various linear velocities. A low mass radiant furnace was employed to maintain the reactor temperatures indicated. Feed rates, conditions and results are indicated on Table 1. Surprising increases in conversion rates are shown at temperatures above 700° C.
- a mixture of 50 weight % propionitrile and 50 weight % of the feed of examples 1-25 was fed into the same reactor as described above.
- the temperature employed was 750° C. and the mole ratio of nitrogen to the mixture of propionitrile and the feed make described above was 0.06.
- Residence time was 1.06 second and the run continued for 53 minutes.
- the conversion of propionitrile was 52% and that of the 70% 4-cyano-suberonitrile was 96%.
- Production of acrylonitrile in the amount of 25 grams of acrylonitrile per 100 grams of the feed mixture was obtained.
- a feed mix consisting of two parts by weight of propionitrile and one part by weight of the 4-cyano-suberonitrile (70 weight %) feed make of examples 1-25 was fed into the same 10 foot reactor. The temperature was maintained at 750° and the mole ratio of nitrogen to the feed mixture was 0.06. 63% of the propionitrile and 99% of the 4-cyano-suberonitrile was converted; and 25 pounds of acrylonitrile per 100 pounds of the feed make was obtained.
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)
Abstract
4-cyano-suberonitrile is continuously converted to acrylonitrile in a catalyst-free reaction at temperatures of about 700°-800° C.
Description
A. Field of the Invention
The invention relates to the production of acrylonitrile from 4-cyano-suberonitrile.
B. The Prior Art
A long standing problem in the manufacture of adiponitrile from acrylonitrile by electrolytic dimerization has been the loss of adiponitrile by way of conversion to the by-products propionitrile and 4-cyano-suberonitrile, which, in a typical electrohydrodimerization reaction, occurs at a rate of about 8-14 mole % of the acrylonitrile employed at a starting material. Of this amount 4-7 mole % is attributable to losses involving conversion of acrylonitrile to the 4-cyano-suberonitrile.
Prior art efforts to recover these losses seem to have focused on the conversion of propionitrile to acrylonitrile; and little, if any attention was apparently given to recovery of acrylonitrile lost in the reactor through conversion to the 4-cyano-suberonitrile.
A reaction for converting the 4-cyano-suberonitrile to acrylonitrile at a commercially acceptable conversion and selectivity rate would be a significant advance in the art and is an object of this invention.
4-cyano-suberonitrile is continuously converted to acrylonitrile by passing the 4-cyano-suberonitrile in atomized form through an esentially oxygen and catalyst-free reaction zone at about 700°-800° C. at an hourly space velocity of about 2400-9300 and a linear velocity of 5-20 ft/sec (152.4-609.6 cm/sec). Within the above ranges, linear velocity and space velocity are adjusted in order to obtain, in relation to the selected temperature, the best conversion rate of 4-cyano-suberonitrile, without sacrifice of an acceptable selectivity rate of the acrylonitrile.
4-cyano-suberonitrile may be employed as feedstock in the relatively impure form in which it is produced by electrohydrodimerization and recovered from the reactor by conventional distillation procedures. Providing it does not contain material deleterious to the reaction or the products, percent of purity is not critical. It is preferably diluted with an inert gas such as nitrogen, or a relatively inert noninterferring diluent such as steam. In order to prevent clogging of nozzles feeding the reactor it may be desirable to use propionitrile as a diluent. The feedstock, pure or diluted, is preferably atomized prior to or during the course of being fed into the reactor but it may be fed in liquid form into the reactor thereafter to be atomized.
We have discovered that thermal conversion of 4-cyano-suberonitrile at temperatures of 700°-800° C., preferably about 740°-800° C. will provide surprisingly higher conversions of the 4-cyano-suberonitrile and higher yields of the acrylonitrile than reactions otherwise similarily conducted at temperatures below about 700° C.
Reactions at such temperatures are conducted continuously at an hourly space velocity of 2400-9300, preferably 2600-8000. "Space velocity" is defined as the volume of gas per hour divided by the reactor volume.
Reactions at these temperatures are conducted at a linear velocity of 5-20 ft/sec (152.4-609.6 cm/sec) preferably 10-15 ft/sec (304.8-457.2 cm/sec) "linear velocity" is defined as the number of cubic units of gas per second divided by the cross sectional area of the reaction zone in square units. The length to diameter ratios of the reactor must be chosen so that the linear and space velocities will come within the requirements of the invention. The volume of 4-cyano-suberonitrile is calculated at the temperature and pressure prevailing in the reactor at operating conditions.
The following examples will serve further to illustrate the process of the invention.
4-cyano-suberonitrile (70.5 wt %) was introduced into a 10 foot (304.8 cm) by 1/4 inch (7.62 cm) stainless steel (304) reactor having a 2 foot × 1/4 inch stainless steel preheater section at temperatures of 650°-750° C. and at various linear velocities. A low mass radiant furnace was employed to maintain the reactor temperatures indicated. Feed rates, conditions and results are indicated on Table 1. Surprising increases in conversion rates are shown at temperatures above 700° C.
TABLE 1
__________________________________________________________________________
EXAMPLE 1 2 3 4 5 6 7
__________________________________________________________________________
Reactor: Temperature
750 750 750 750 750 750 750
cc Void 47.8
47.8
47.8
47.8
47.8
47.8
47.8
Feed Rate: Liq. cc/hour
240.9
240.9
508.5
250 392.1
273.7
428.6
Liter N.sub.2 /hour
2.0 2.0 3.5 2.0 3.5 3.5 3.5
g/hour
N.sub.2 Feed Mole Ratio
0.06
0.06
0.05
0.06
0.06
0.06
0.06
Space Velocity: at Reactor Temp- -hr
2632
2632
5828
2887
4557
3664
4956
Liq. hourly-cc/hr/cc Cat
5.04
5.04
10.6
5.23
8.21
5.73
8.97
Contact Time - sec.
1.37
1.37
0.62
1.25
0.79
1.10
0.72
% Conversion to 4-cyano-suberonitrile
** 99.9
** ** ** 98.8
**
Accountability (moles per 100 moles 4-
84.9
** 84.8
87.3
75.0
** 83.5
cyano-suberonitrile converted)
Acrylonitrile 30.9
** 28.2
30.4
25.9
** 28.6
HCN 3.4 ** 2.1 3.1 2.04
** 2.4
CH.sub.2 CN 14.9
** 10.8
14.8
9.7 ** 11.8
Ethylene 3.3 ** 2.7 4.5 4.4 ** 3.0
Ethane 0.3 ** 0.2 0.4 0.4 ** 0.4
Methane 0.8 ** 0.5 1.2 0.9 ** 0.5
Propionitrile 5.2 ** 4.8 4.8 3.8 ** 4.7
AN/HCN Mole Ratio 4.70
** 6.72
5.0 6.5 ** 6.0
Linear Vel., Ft/Sec.
5.6 5.6 12.5
6.2 9.8 7.0 10.6
Linear Vel., Cm/Sec.
170.69
170.69
381 188.98
298.70
213.36
323.09
The feed make was as follows:
4-cyano-suberonitrile
:
70 wt. %
adiponitrile :
2.5 wt. %
other materials
:
27 wt. %
EXAMPLE 8 9* 10* 11* 12* 13* 14*
__________________________________________________________________________
Reactor: Temperature
750 650 650 650 650 650 650
cc Void 47.8
47.8
47.8
47.8
47.8
47.8
47.8
Feed Rate: Liq. cc/hour
447.8
461.5
461.5
231.7
442.9
149.3
147.8
Liter N.sub.2 /hour
3.5 3.5 3.5 1.9 1.9 1.2 1.2
g/hour 467.4
481.8
481.8
241.8
253.6
155.8
154.3
N.sub.2 Feed Mole Ratio
0.06
0.05
0.05
0.06
0.06
0.06
0.06
Space Velocity: at Reactor Temp- -hr
5165
4796
4796
2417
2528
1471
1541
Liq. hourly-cc/hr/cc Cat
9.37
9.66
9.66
4.85
5.08
3.12
3.09
Contact Time - sec.
0.70
0.75
0.75
1.48
1.42
2.45
2.34
% Conversion to 4-cyano-suberonitrile
95.8
** 40.6
** 49.6
** **
Accountability (moles per 100 moles 4-
** 84.1
** 94.0
** 68.4
78.5
cyano-suberonitrile converted)
Acrylonitrile ** 7.6 ** 12.6
** 13.1
14.4
HCN ** 0.4 ** 0.8 ** 0.8 0.8
CH.sub.2 CN ** 3.7 ** 5.8 ** 6.0 6.7
Ethylene ** 0.2 ** 0.6 ** 0.8 1.2
Ethane ** 0.02
** 0.1 ** 0.1 0.2
Methane ** 0.07
** 0.2 ** 0.2 0.3
Propionitrile ** 2.4 ** 3.4 ** 3.3 3.7
AN/HCN Mole Ratio ** 9.9 ** 8.2 ** 8.6 8.8
Linear Vel., Ft/Sec.
11.1
10.3
10.3
5.2 5.4 3.2 3.3
Linear Vel., Cm/Sec.
338.33
313.94
313.94
158.39
164.59
97.53
100.58
EXAMPLE 15 16 17 18 19 20 21
__________________________________________________________________________
Reactor: Temperature
650*
700 700 700 700 700 700
cc Void 47.8
47.8
47.8
47.8
47.8
47.8
47.8
Feed Rate: Liq. cc/hour
147.4
363.6
397.4
309.8
288.5
219.8
225.6
Liter N.sub.2 /hour
1.2 3.6 3.6 2.4 2.4 1.7 1.7
g/hour 153.9
379.6
414.8
322.9
301.1
229.4
235.5
N.sub.2 Feed Mole Ratio
0.06
0.07
0.07
0.05
0.06
0.06
0.05
Space Velocity: at Reactor Temp- -hr
1538
4046
4397
3679
3176
2410
2471
Liq. hourly-cc/hr/cc Cat
3.08
7.61
8.32
6.47
6.04
4.60
4.72
Contact Time - sec.
2.34
0.89
0.82
0.98
1.13
1.49
1.45
% Conversion to 4-cyano-suberonitrile
62.6
** 68.3
** 74.4
** 81.9
Accountability (moles per 100 moles 4-
** 94.5
** 80.5
** 76.0
**
cyano-suberonitrile converted)
Acrylonitrile ** 21.1
** 21.5
** 23.0
**
HCN ** 1.4 ** 1.4 ** 1.6 **
CH.sub.2 CN ** 9.0 ** 9.2 ** 10.1
**
Ethylene ** 1.9 ** 1.3 ** 1.5 **
Ethane ** 0.3 ** 0.2 ** 0.2 **
Methane ** 0.4 ** 0.3 ** 0.3 **
Propionitrile ** 4.5 ** 4.5 ** 4.6 **
AN/HCN Mole Ratio ** 7.5 ** 7.7 ** 7.1 **
Linear Vel., Ft/Sec.
3.3 8.7 9.4 7.9 6.8 5.2 5.3
Linear Vel., Cm/Sec.
100.58
265.18
286.51
240.79
207.26
158.5
161.54
EXAMPLE 22 23 24 25
__________________________________________________________________________
Reactor: Temperature
700 700 750 750
cc Void 47.8
47.8
47.8
47.8
Feed Rate: Liq. cc/hour
845.1
857.1
805.4
797.9
Liter N.sub.2 /hour
7.1 7.1 6.7 6.7
g/hour 882.2
894.8
840.7
832.9
N.sub.2 Feed Mole Ratio
0.06
0.06
0.06
0.06
Space Velocity: at Reactor Temp- -hr
9309
9434
9327
9240
Liq.hourly-cc/hr/cc Cat
17.7
17.9
16.9
16.7
Contact Time - sec.
0.39
0.38
0.39
0.39
% Conversion to 4-cyano-suberonitrile
** 41.8
** 90.4
Accountability (moles per 100 moles 4-
92.2
** 73.7
**
cyano-suberonitrile converted)
Acrylonitrile 12.6
** 22.1
**
HCN 0.7 ** 1.5 **
CH.sub.2 CN 5.4 ** 9.0 **
Ethylene 0.9 ** 1.9 **
Ethane 0.2 ** 0.2 **
Methane 0.1 ** 0.4 **
Propionitrile 3.0 ** 4.1 **
AN/HCN Mole Ratio 8.9 ** 7.5 **
Linear Vel., Ft/Sec.
20.0
20.2
20.0
19.8
Linear Vel., Cm/Sec.
609.6
615.7
609.6
603.5
__________________________________________________________________________
*Comparison examples
**Conversion measurements and acountability and analysis measurements
were made alternately due to limited quantities available.
A mixture of 50 weight % propionitrile and 50 weight % of the feed of examples 1-25 was fed into the same reactor as described above. The temperature employed was 750° C. and the mole ratio of nitrogen to the mixture of propionitrile and the feed make described above was 0.06. Residence time was 1.06 second and the run continued for 53 minutes. The conversion of propionitrile was 52% and that of the 70% 4-cyano-suberonitrile was 96%. Production of acrylonitrile in the amount of 25 grams of acrylonitrile per 100 grams of the feed mixture was obtained.
A feed mix consisting of two parts by weight of propionitrile and one part by weight of the 4-cyano-suberonitrile (70 weight %) feed make of examples 1-25 was fed into the same 10 foot reactor. The temperature was maintained at 750° and the mole ratio of nitrogen to the feed mixture was 0.06. 63% of the propionitrile and 99% of the 4-cyano-suberonitrile was converted; and 25 pounds of acrylonitrile per 100 pounds of the feed make was obtained.
Claims (7)
1. A continuous process for producing acrylonitrile from 4-cyano-suberonitrile comprising passing 4-cyano-suberonitrile in atomized form through an essentially oxygen and catalyst-free reaction zone at a temperature of about 700°-800° C., an hourly space velocity of 2400-9300 and a linear velocity of 5-20 ft/sec.
2. The continuous process of claim 1 wherein the catalyst free reaction zone is maintained at a temperature of 740°-800° C.
3. The continuous process of claim 1 wherein the reaction zone is maintained at a temperature of about 750° C.
4. The continuous process of claim 1 wherein the hourly space velocity is about 2600-8000.
5. The continuous process of claim 1 wherein the linear velocity is about 10-15 ft/sec.
6. The continuous process of claim 1 wherein the catalyst-free reaction zone is maintained at a temperature of about 750° C., the hourly space velocity is about 2600-8000, and the linear velocity is about 10-15 ft/sec.
7. The continuous process of claim 1 wherein the 4-cyano-suberonitrile is diluted with propionitrile before being converted to acrylonitrile.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US05/846,100 US4128571A (en) | 1977-10-27 | 1977-10-27 | Thermal conversion of 4-cyano-suberonitrile to acrylonitrile |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US05/846,100 US4128571A (en) | 1977-10-27 | 1977-10-27 | Thermal conversion of 4-cyano-suberonitrile to acrylonitrile |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US4128571A true US4128571A (en) | 1978-12-05 |
Family
ID=25296943
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US05/846,100 Expired - Lifetime US4128571A (en) | 1977-10-27 | 1977-10-27 | Thermal conversion of 4-cyano-suberonitrile to acrylonitrile |
Country Status (1)
| Country | Link |
|---|---|
| US (1) | US4128571A (en) |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2452505A (en) * | 1943-06-23 | 1948-10-26 | Sinclair Refining Co | Dehydrogenating saturated nitriles to unsaturated nitriles |
| US2671107A (en) * | 1951-06-26 | 1954-03-02 | Sinclair Refining Co | Catalytic dehydrogenation of aliphatic nitriles |
| US3247237A (en) * | 1963-07-01 | 1966-04-19 | Eastman Kodak Co | Production of acrylonitrile and methacrylonitrile by the thermal cracking of saturated nitriles |
| US3267131A (en) * | 1964-04-27 | 1966-08-16 | Monsanto Co | Product separation and recovery in adiponitrile manufacture |
| US3280168A (en) * | 1964-07-09 | 1966-10-18 | Monsanto Co | Catalytic acrylonitrile production |
-
1977
- 1977-10-27 US US05/846,100 patent/US4128571A/en not_active Expired - Lifetime
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2452505A (en) * | 1943-06-23 | 1948-10-26 | Sinclair Refining Co | Dehydrogenating saturated nitriles to unsaturated nitriles |
| US2671107A (en) * | 1951-06-26 | 1954-03-02 | Sinclair Refining Co | Catalytic dehydrogenation of aliphatic nitriles |
| US3247237A (en) * | 1963-07-01 | 1966-04-19 | Eastman Kodak Co | Production of acrylonitrile and methacrylonitrile by the thermal cracking of saturated nitriles |
| US3267131A (en) * | 1964-04-27 | 1966-08-16 | Monsanto Co | Product separation and recovery in adiponitrile manufacture |
| US3280168A (en) * | 1964-07-09 | 1966-10-18 | Monsanto Co | Catalytic acrylonitrile production |
Non-Patent Citations (1)
| Title |
|---|
| Arira et al., C.A., 72 (1970), 85681g. * |
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|---|---|---|---|
| AS | Assignment |
Owner name: SOLUTIA INC., MISSOURI Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:MONSANTO COMPANY;REEL/FRAME:008820/0846 Effective date: 19970824 |